Image quality in radiographic and fluoroscopic (X-ray) imaging systems is determined by a set of physical parameters such as noise, contrast, spatial resolution, etc., and it is affected by the signal transfer functions of individual system components such as the X-ray tube, image detector, video processor, digital processor, etc. Moreover, the imaging performance of the system is not only affected by the performances of the individual components, but also by their interaction. The variability of the interaction can be greatly affected by calibration of these systems during manufacturing and at their installation sites. It was previously often found that radiographic/fluoroscopic systems (and more specifically their video imaging systems) suffered from degraded image quality once they were assembled at their installation sites, even though the components of these systems had undergone extensive factory calibration. This occurred even where components were calibrated both individually (to account for their individual transfer functions) and taken together (to account for their collective transfer functions). This image degradation at the installation site led to greatly increased costs because the systems would then need to undergo extensive field recalibration and/or replacement of system components that were suspected of being defective. There was therefore a substantial need for apparata and methods for allowing rapid recalibration so that image quality could be optimized.